Best spec? [PVE]

I'm back to WoW now. I left it in June after raiding in Throne and now I don't know the updates and changes.
I was Assassination (I have 513ilvl) and I haven't tried in Orgrimmar. I don't know any other PvE Rogue so I don't know who should I ask so I ask you.
Which is the best spec for PvE and why? My favourite is combat but I want to max my DPS. I have weapons for every spec.

I also want to know if it's really good for PvE or I should reroll to my Warrior or my Priest. Thank you everyone!

Also see the stickies or the PvE guide posted at the top. Raidbots should help you see how rogues compare in total DPS vs. other classes. In a shorter response, rogues are doing absolutely fine as DPS in PvE.

Closing this as any relevant discussion belongs in another existing thread.